Rotary kiln



N. S. BORCH ROTARY '1mm4 April 9, 1940.

Filed Sept. 23, 1938 2 Sheets-Sheet 1 www, Mlfsm@ April 9 1940. N. s. BoRcH 2,196,245

' ROTARY KILN v I Filed Sept. 23, 1938 2 Sheets-Sheet 2 ATTORNEYS Patented Apr. 9, 1940 UNHTED- STATES;

'N i'els Sofus'Borch, Copenhagen, Denmark, as-

signor to F. L. Smidth & Company, New York,v

N. Y., acorporation of-New Jersey Application-september 23, 193s, serial No. 231,335 f4 claims. (cl. zes-3 2) This invention is rrelated to rotary kiln installations, such as are employed for sintering and agglomerating purposes, and has to do more particularly with a novel device used in such an s, installationA for directing the hot material discharging iromthe kiln to the outlet to the cooler.

vIn the treatment of nely divided materials, such'as pulverulent iron ore, vblast furnace dust, and the like,`insintering andagglomerating kilns,

in the materials, when heated to the proper temperature, become somewhat tacky so that` the y particles coh'ere and also tend to stick tothe kiln lining and form crusts thereon. Such accumulations must be removed `from time to time,

i5 and, accordingly, to avoid interruptionsin operation, the kiln is operated in such manner vthat the sintering zone Ais short and as near lthe outlet end of the -kiln as possible. Under-,such conditions, the lining in the Zone of ihighest o temperaturemay be'kept clean by a suitable tool manipulated from outside the kiln, as,.for eX- ample, by means of a water-cooled rod provided with a knife which is `inserted into ythe'kiln through the outlet` end and is operated to break 9 `the crust loose.

d Since the sin'tering zone in such kilns is im mediately ahead of the vdischarge end, the material issuing from the kiln is very hot and tends to adhere to surfaces with which itmay contact ing ,it-to a cooler, the device being so constructed' that-.the surfaces thereof with which the hot 45 material contacts are kept cool and chill the material so that the latter will not adhere thereto; The new device may take various forms, but ordinarily it rincludes a plurality of walls disposed in a hood at the discharge end of the m kiln'and leading to an outlet passage from the hood to the cooler. l These walls are provided with cooling means which may conveniently take the i'orzn of conduitslformed therein and constituting passages for a cooling medium. Suchv conduits 5,; may be made in various Ways as, for example, by

cordance with the invention;

..0 onits way to the cooler. If an ordinary hopper cores vplaced in arnold in which the `walls are cast, or the walls maybe made of sheet metal forming a chamber provided with internalparti-N reference may be made to the accompanying drawings, in which I Figure 1 is a longitudinal section through a portion ofthe discharge end of a rotary kiln :To and its hoodthe latter-being constructed in 'ac- `Figure 2 isa Asectional view on the line 2 2 of Figurelyand Figure 3 is a sectional View showing a mo'dif5 ed wall construction. H

Referring to the drawings, Athe installation as illustrated. includes a rotary kiln -IIl having a llining l I provided at its discharge end with a section I 2 which enters an'opening in onewall 20 of a movable hood I3 mounted'on wheels I4 on a track I Surroundingy vthe opening in the hood through which the end of the kilnprojects is a chamber I6 forming part of a conventional sealing device which includes an annular disc ll contacting `withthe outer surface of arranged to direct its name into the lend of the kiln. v

, At the lower end of the hood are mounted a pair ofI downwardly converging lateral walls I9 which, in the construction shown, are supported 35 at their lower ends on hollow outlet members 120, 2l, lying one upon the other and'resting on a .plate 22 carried by the axles 23 of wheels I4.

rihe walls I9 are supported in inclined position at their upper ends by brackets 24 attached tov 4 0 the side walls of the hood. Within the walls lli are conduitsv 2e for a cooling uid, each conduit havinginlet and outlet connections 21,' 28, respectively, which lead through the side walls 25 ofthe hood.

` 45 Directly beneath the end of the section I2 of Athe kiln is a plate 29 curved to conform to the shape of the section, and a downwardly sloping wall 38 below the plate 29 leads to the outlet opening through the members 20, 2I. Both f50 plates E@ and 3G are provided -with conduits-3l,

for the'passage of a cooling Iluid and these conduits inlet and outlet connections 33,

34 leading through the side walls 25 of the hood.

The outlet member 2@ is formed with a forward 55 fr D extension 35 serving as a floor plate, and both this member and the member 2| are provided with internal conduits 36 for a cooling medium supplied to the conduits and withdrawn therefrom through connections not shown. The floor plate 35 serves as a means for catching discharging material which may not pass at once through the outlet passage through the members 20, 2l, the material so collected forming a pile which protects the plate from Wear. Also, the plate facilitates removal of clinker lumps too large to pass through the outlet.

The outer end wall 25a of the hood has an opening directly above the oor plate 35, and mounted in the opening is a frame 31 on which a door 38 is pivoted. The frame may, if desired, be formed with a cooling medium conduit 3S having inlet and supply connections, not shown.

With the construction described, the hot material issuing from the kiln passes over the surfaces of plate 29 and along the walls I9, 30, to the outlet passage formed through the members 20, 2 l, and the material falls through the passage and through a passage 40 to the usual cooler. All the surfaces inside the hood with which the hot material may come into contact are cooled by the circulating cooling medium and these surfaces are kept at such a temperature that they lower the temperature of the hot material to a' point where it loses its tendency to adhere. As a result, the material passes freely through the hood and outlet passages and, accordingly, no Caking up on the Walls or floor of the outlet de- Vice and no clogging of the outlet occur.

In the construction shown in Figures 1 and 2, the walls and outlet members are illustrated as having conduits for the cooling medium embedded therein, and such walls may readily be made by a casting operation, during which the conduits are formed by the use of cores. If desired, however, the walls may be made of sheet metal, and for this purpose, pieces of sheet metal of the proper shape and size are welded together to form a chamber 4| of the desired dimensions. Before the chamber is closed, partitions 42 of sheet metal are mounted in place therein so as to provide a tortuous passage. An inlet 43 and an outlet 44 for cooling fluid are then mounted in the walls of the chamber in such manner that the cooling uid must travel through the passage from end to end from the inlet to the outlet. A sheet metal wall thus constructed serves the same purpose as those illustrated in Figures 1 and 2, and may be of considerably lighter weight.

I claim:

1. In a hood for use with a rotary kiln, the combination of a chamber having an opening through which the discharge end of the kiln projects, a horizontal oor plate at the bottom of the chamber, an outlet passage leading from an opening in the plate, a plurality of converging walls leading toward said opening, the hot material issuing from the kiln passing along the walls to the outlet passage, and passages for a cooling medir-.1n within said converging walls, floor plate, and the walls of the outlet passage.

2. In a hood for use with a rotary kiln, the combination of a chamber having an opening through which the discharge end of the kiln projects, a horizontal floor plate at the bottom of the chamber, an outlet passage leading from an opening in the plate, a plruality of converging walls leading toward said opening, the hot material issuing from the kiln passing along the walls to the outlet passage, a frame surrounding an opening in a wall of the chamber adjacent the floor plate, a door for the opening, and passages for a cooling medium within said converging walls, iioor plate, frame, and the walls of the outlet passage.

3. In a hood for use with a rotary kiln having an opening into which the discharge end of the kiln projects, the combination of an inclined wall leading downwardly and away from said end of the kiln, a pair of walls each lying at an angle to said inclined wall and converging downwardly, a horizontal oor plate below said walls having an outlet opening, the hot material issuing from the kiln passing along the inclined and converg- I ing walls to the opening, and means for cooling said walls and plate.

4. A hood for use with a rotary kiln comprising walls forming a chamber into which the discharge end of the kiln projects through an opening, the chamber being mounted on wheels and i movable toward and away from the kiln, and a discharge device mounted in the chamber below the end of the kiln and comprising a floor plate having an outlet therethrough for discharging,1

material, a rear wall inclined from the end ol the kiln to the floor plate adjacent the outlet. a pair of lateral walls converging downwardly to the outlet, the material issuing from the kilns moving along the walls to the outlet and the floor plate collecting material which fails to pass through the outlet, and passages for a cooling medium within said walls, the oor plate, and the walls of the outlet for cooling the surfaces of the walls and plate to prevent adherence of the dis 

